In vivo dynamics and differential microtubule-binding activities of MAP65 proteins
In vivo dynamics and differential microtubule-binding activities of MAP65 proteins
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DOI：
10.1104/pp.104.051623
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发表时间：
2004-12-01
期刊：
影响因子：
7.4
通讯作者：
Geelen, D
中科院分区：
文献类型：
--
作者：
Van Damme, D;Van Poucke, K;Geelen, D
植物细胞产生不同的微管阵列，这些微管阵列对于细胞分裂和形态发生是必不可少的，而在其他真核生物中没有等同物。微管相关蛋白影响微管的行为，推测微管的行为最终会从一个阵列过渡到另一个阵列。我们分析了微管结合特性的三个拟南芥（拟南芥）的成员，AtMAP 65 -1，AtMAP 65 -4，和AtMAP 65 -5，在活细胞中使用激光扫描共聚焦显微镜。根据皮质阵列的整体组织，AtMAP 65 -1-GFP（绿色荧光蛋白）和AtMAP 65 - 5 GFP与微管的子集相关。在含有共排列和倾斜微管的细胞中，AtMAP 65 -1-GFP和AtMAP 65 -5-GFP倾向于与共排列的微管相关联。用AtMAP 65 -1GFP和AtMAP 65 -5-GFP标记的皮质微管呈粗束状，对微管去稳定化药物表现出更强的抗性。AtMAP 65 -1-GFP和AtMAP 65 -5-GFP微管的聚合速率与微管蛋白-GFP标记的微管的聚合速率相似，但与AtEB 1a-GFP不同，AtEB 1a-GFP是一种微管加末端结合EB 1样蛋白，刺激聚合。相反，AtMAP 65 -1-GFP-和AtMAP 65 -5-GFP-标记的微管的解聚速率降低。AtMAP 65 -1-GFP与在束内聚合微管和固定微管末端相关，表明AtMAP 65 -1的功能是捆绑和稳定皮质的相邻微管。在一束聚合发生在任何一个方向，使集束之间发生平行或反平行排列的微管。AtMAP 65 -4-GFP没有标记皮质微管或preprophase带，尽管连续表达驱动的35 S启动子，其亚细胞定位被限制在微管重新排列，形成一个纺锤体和极侧的纺锤体适当。AtMAP 65 -4的表达在有丝分裂时达到峰值，与纺锤体形成相关的功能一致，而AtMAP 65 -1和AtMAP 65 -5在整个细胞周期中表达。
Plant cells produce different microtubule arrays that are essential for cell division and morphogenesis without equivalent in other eukaryotes. Microtubule-associated proteins influence the behavior of microtubules that is presumed to culminate into transitions from one array to another. We analyzed the microtubule-binding properties of three Arabidopsis (Arabidopsis thaliana) members, AtMAP65-1, AtMAP65-4, and AtMAP65-5, in live cells using laser scanning confocal microscopy. Depending on the overall organization of the cortical array, AtMAP65-1-GFP (green fluorescent protein) and AtMAP65-5GFP associated with a subset of microtubules. In cells containing both coaligned and oblique microtubules, AtMAP65-1-GFP and AtMAP65-5-GFP tended to be associated with the coaligned microtubules. Cortical microtubules labeled with AtMAP65-1GFP and AtMAP65-5-GFP appeared as thick bundles and showed more resistance to microtubule-destabilizing drugs. The polymerization rates of AtMAP65-1-GFP and AtMAP65-5-GFP microtubules were similar to those of tubulin-GFP marked microtubules but were different from AtEB1a-GFP, a microtubule plus-end-binding EB1-like protein that stimulated polymerization. By contrast, depolymerization rates of AtMAP65-1-GFP- and AtMAP65-5-GFP-labeled microtubules were reduced. AtMAP65-1-GFP associated with polymerizing microtubules within a bundle, and with fixed microtubule termini, suggesting that AtMAP65-1's function is to bundle and stabilize adjacent microtubules of the cortex. Polymerization within a bundle took place in either direction so that bundling occurred between parallel or antiparallel aligned microtubules. AtMAP65-4-GFP did not label cortical microtubules or the preprophase band, despite continuous expression driven by the 35S promoter, and its subcellular localization was restricted to microtubules that rearranged to form a spindle and the polar sides of the spindle proper. The expression of AtMAP65-4 peaked at mitosis, in agreement with a function related to spindle formation, whereas AtMAP65-1 and AtMAP65-5 were expressed throughout the cell cycle.